[Info-vax] TCP/IP V5.6 ECO 4 caveat...

[Jan-Erik Söderholm]

VAXman- @SendSpamHere.ORG wrote:
> I've looked at two Alpha crashes today.  Both were the results of kernel
> code that accesses telnet devices.  The problem seems to be that a TCPIP
> ECO (TCPIP V5.6 ECO4) trounces on R4 when calling IOC$SEACTHDEV.  Below
> is the comment header from the source listings for this routine.  I took
> the liberty of deleting the listing lines so that this will fit into 80
> columns.
> 
> ;+
> ;
> ; IOC$SEARCH - general I/O database search
> ; IOC$SEARCHDEV - search for specific physical device
> ; IOC$SEARCHALL - generic search for any device
> ;
> ; This routine searches the I/O database for the specified device, using
> ; the specified search rules. Depending on the search, a lock may or may
> ; not be taken out on the device when it is found.
> ;
> ; INPUTS:
> ;
> ;       R1 = address of descriptor of device / logical name string
> ;       R2 = flags
> ;       R3 = address to store lock value block
> ;       I/O database mutex held, IPL 2
> ;
> ; OUTPUTS:
> ;
> ;       R0 = SS$_NORMAL - device found
> ;          = SS$_ACCVIO - name string is not readable
> ;          = SS$_NONLOCAL - nonlocal device
> ;          = SS$_IVLOGNAM - invalid logical name (e.g., too long)
> ;          = SS$_TOOMANYLNAM - max. logical name recursion exceeded
> ;          = SS$_IVDEVNAM - invalid device name string
> ;          = SS$_NOSUCHDEV - device not found
> ;          = SS$_NODEVAVL - device exists but not available according to rules
> ;          = SS$_DEVALLOC - device allocated to other user
> ;          = SS$_NOPRIV - failed device protection
> ;          = SS$_TEMPLATEDEV - can't allocate template device
> ;          = SS$_DEVMOUNT - device already mounted
> ;          = SS$_DEVOFFLINE - device marked offline
> ;       R1 = UCB
> ;       R2 = DDB
> ;       R3 = system block
> ;       R4 - R11 preserved
> ========^^================ Don't you believe it!
> ;
> ;       Note: If failure, R1 - R3 point to the last structures looked at.
> ;
> ;       R2 and R3 are input only to IOC$SEARCH.
> ;
> ;       IOC$SEARCHDEV:  R2 = IOC$M_PHY ! IOC$M_ANY
> ;                       R3 = 0
> ;       IOC$SEARCHALL:  R2 = IOC$M_ANY ! IOC$M_LOCAL
> ;                       R3 = 0
> ;
> ;-
> 
> The crashes occurred after calling IOC$SEARCHDEV with a telnet device and
> then accessing the PCB which should have been preserved in R4 across this
> call according to the documentation.  This particular bit of code has been
> in production for decades and only with installation of TCPIP V5.6 ECO 4
> has there been any issue.  I've fixed the code by preserving R4 across the
> IOC$SEARCHDEV.  This problem only occurs when accessing TCPIP devices and
> not with any other terminal device.
> 
> Just a heads up!
> 

Is this only happening when using self-written code that calles
this routines ? Or have you seen this when using the usual DCL
interfaces to TCPIP/Telnet ? That is "telnet create", "telnet
delete" and so on ?

Jan-Erik.